Shaping-machine for screw-propellers.



A. MiT HLBERG.

SHAPING MACHINE FDR SGREW PROPELLERS.

APPLICATION FILED 11110.2, 1909.

Patented A r. 2, 1912.

3 SHEETS-SHEET 1.

COLUMBIA PLANOGRAPll CUWASHINGTON. D. c.

A. MUHLBERG.

SHAPING MACHINE FOR SCREW PROPELLERS.

APPLICATION FILED DBO. 2, 1909. I

Patented Apr. 2, 1912.

a SHEETS-SHEET 2.

I W/T/VESSES.

ff/m w/ COLUMBIA PLANOORAPH 50.. WASHINGTON, D4 c. v

12211101111011 FILED DEC. 2, 1909 Patented Apr. 2, 1912.

3 SHEETS-SHEET 3.

W/T/VES'SES UNITED STATES PATENT OFFICE.

ALBERT Mfi'HLBE RG, or BASED, SWITZERLAND.

SHAPING-MACHINE FOR SGREW-PRQPELLERS.

Specification of Letters Patent.

Patented Apr. 2, 1912.

Original application filed December 31, 1908, Serial No. 470,167. Divided and. this application filed December 2, 1909.

Serial No. .'530,915.

To all whom it may concern:

Be it known that I, ALBERT Mt'IHLBnRc, a

citizen of the Swiss Republic, and resident of Basel, Switzerland, engineer, have invented new and useful Improvements in- Shaping-Machin'es for Screw-Propellers, of which the following is a full, clear, and exact specification.

The present invention relates to shaping machines for blade screw propellers of the kind described in my application for Letters Patent Ser. No. 4:7 0,167, wherein the pressure surface of the blades is of such concave shape that the angle of pitch which it forms with the plane of revolution, changes peripherally from point to point in a concentric blade sect-ion, but is nevertheless everywhere equally large, from entrance to exit, in a plane of intersect-ion perpendicular to the radiusvector of the entering point and to the plane of revolutiomthis particular form of the pressure surface of the blades having many advantages as indicated inthe aforesaid application for Letters Patent. The automatic shaping of such screw propeller blades is of great advantage in so far as it allows to obtain a smooth surface and to thus reduce the coefficient of friction between the water and the pressure "surface. The shaping of such screw propeller blades is based upon the following considerations: If we imagine a propeller blade of the aforesaid kind being mounted between two rotary points or face plates, so that it may revolve in such a manner that the blade can be turned around the entering radius vector of the line system forming the pressure surface and if we imagine further a fixed plane being laid through this radius vector and the axis of revolution of'the screw, the several relative paths, forming the pressure surface of the blade, may be folded successively into this fixed plane by turning the bladearound the complement a of the angle of pitch E5. If now, for instance, we allow to move to and fro a planing tool, cutter or the like in this fixed plane, a planing of the pressure surface of the blade is possible under the assumption that the tool in the radial direction of the bladeis always exactly at that spot where the relative path coincides with the fixed plane, that is to say, that the cross feed of the tool and the revolution of the blade must be in a determinate ratio to each other. Accordingly the present shaping machine is arranged in such a manner that the blade to be shaped is revolved in a determinate ratio with the feed of the cutting tool moving in a plane, which feed takes place in the radial direction of the blade, so that the surface strips 'of the pressure surface of the blade to be shaped fall successively into the cutting plane of the tool during the continuance of the cut..

The accompanying drawing represents an embodiment of the improved shaping machine for screw propeller blades of the aforesaid kind.

Figure 1 is a front view, Fig. 2 a side view and Fig. 3 a plane view of this machine. Fig. i shows details on a larger scale. Fig. 5 shows in section on a larger scale a coupling device for the face plates. Fig. 6 represents a modification of this coupling device. Figs. 7 and 8 show in side elevation and in plan View, respectively, a pawl mechanism for feeding the tool carriage.

Figs. 9 and 10 illustrate the mechanism for erence to Figs. 9 and 10. The feed of the tool carriage a across the cutting direction is efi'ected by a feeding screw spindle f which is set in motion in the well known manner in one direction or the other by a pawl mechanism on the return travel of the carriage a. The carriage a carries in front, in an adjustable tool carrier, the planing or shaping tool 6. The driving mechanism for producing the to-and-fro movement of the tool carriage a has for example the following arrangement (see Figs. 9 and 10) :On a shaft R driven from the main pulley T through a gearing S is mounted a gear wheel Q, coupled with said shaft by means of a key and groove connection, so as to partake of the rotation of said shaft. In the axial direction, however, the wheel Q, is capable of displacement on the shaft R according to the feeding movement of the slide P formed with the guide-way for the tool carriage a and carrying the wheel Q. The slide P is moved by the aforesaid feeding spindle f for the feed movement of the tool carriage (t. The wheel Q meshes with a toothed wheel 0 supported in the slide P and having a crank pin N engaging with a slot in an oscillating lever M connected to the shaft A by means of a key and groove connection, said lever M being connected at its upper end by means of a link to a transverse bolt U of the tool carriage a. By these means, when the shaft B rotates, it imparts through the crank wheel 0 and the lever M a reciprocating movement to the tool carriage a. in the slide P, whereby the whole driving mechanism is also capable of following the feeding movement of the tool carriage a owing to the key and groove connections of the wheel Q, and the lever M with their respective shafts R and A.

An example of the aforesaid pawl mechanism for the feed of the tool carriage a is represented in Figs. 7 and 8. On the oscillating shaft A of the machine, carrying the lever for moving to and fro the tool carriage a, is keyed an arm B connected by a rod 0 to a pawl lever F loosely rotatable on the spindle f, so that the pawl lever F receives an oscillating motion. on opposite sides of the spindle f two pawls D corresponding to two ratched wheels G fixed on the spindle According as the one or the other ofthe said pawls D is brought into engagement with its corresponding ratched wheel G, the spindle f is turned in the one or other direction on the return travel of the tool carriage a.

The mounting table of the machine has two hearings in which are rotatably supported two face plates 0, which hold between them the blade r to be shaped. The screw blade is to be mounted in such a manner between the said face plates 0 that the radius vector on the entering side upon which the straight or relative paths forming the pressure surface are perpendicular, coincides with the axis of rotation of the face plates 0.

The two face plates 0 may be revolved in a uniform manner by toothed sectors (5 gearing into two racks p mechanically coupled with each other. In order however, to make it possible to mount the part to be shaped in a convenient manner, the face plates 0 are coupled with the toothed sectors d by a coupling device hereinafter described which can be engaged or released by means of handwheels 6, so that for mounting the work the face-plates 0 may be released from the toothed sectors d, the coupling being effected only after the blade has been properly mounted and the machine adjusted.

The device for coupling the face plates 0 with the toothed sectors (2 may be of any desired construction. Two forms thereof are represented in Figs. 5 and 6.

In the device of Fig. 5 each face plate a The lever F carries carries at the end of its supporting nave a toothed gear J, the teeth of which mesh with a similar toothing J of the sector (Z when the coupling is engaged. Thus, the face plate 0 and the sector (Z are rigidly connected together. The sector (Z is capable of being shifted axially, by means of the hand wheel 6 connected thereto and screwed on a threaded part, so that its toothing J can be brought out of engagement with the toothed gear J, without having the peripheric teeth of the sector disengaged from the corresponding rack p. When the sector (Z is thus disengaged from the face plate 0, the latter is capable of being freely turned. Before engaging the coupling, care must be taken that the two toothed parts to be engaged one with another have the convenient relative position to allow of this engagement. This may be, in certain cases, disadvantageous. To obviate this disadvantage, the face plate 0 is provided in the modification according to Fig. 6 with a friction cone J 0 arranged to cooperate with a corresponding hollow rim J on the toothed sector cl, so that the thus formed friction coupling can be engaged in any position of the parts.

The connection of the feed spindle f of the tool carriage a with the revolving device for the blade to be shaped is made in the following manner: The feed spindle f drives by means of reversing gear 9, shaft 71 and change gear 6 (Fig. 2), a vertical screw spindle 0, which alters the position, in vertical direction, of a movable slide Z, according to the transverse motion of the tool carriage a. The said slide Z has a pivot m, which is adjustable horizontally by means of hand Wheel 9 and which enters a sliding part arranged in a groove of a lever n. and thereby imparts to the latter an angular displacement upon its shaft ]a,when the slide Zmoves in a vertical direction. The lever a which is mounted at one end of the shaft 72 is further provided with a toothed sector m, which gears into a rear toothing of one of the racks 79. By means of the shaft is and a toothed sector :0 at its other end is also moved simultaneously the rack p on the opposite side, so that both face plates have an absolutely identical motion. If the toothed sectors (Z are coupled with the face plates 0, the latter turn over the same angle or as the lever 12 It may now be seen that the angle a over which the lever 01, m and the face plates 0 are turned, is only dependent on the vertical displacement of the slide Z, which in its turn depends on the radial movement crosswise of the tool carriage a as well as on the horizontal distance Lat which the pivot m is adjusted. Therefore, by varying the ratio of transmission between the spindles f and 0 and by altering the distance L it is possible to obtain any desired pitch.

For the purpose of controlling the adjustment the absolute values of B and L may be read by means of pointer and scale, asshown in Fig. 4. For the practical use of the machine it will be advisable to adopt a table in which is indicated, for all pitches that may occur, how the distance L and the ratio of transmission of the change gear 2' is to be set. So for instance all screw blades with any desired pitch between 2.7 and'12.5 meters and for radial length of the blade surface to be worked of from 1.4 to 4 meters may be worked by means of three transmission of the change gear 2' and with a distance L of from 300 to 500 millimeters and a maximum travel of the slide Z of 1000 millimeters. The mounting and subsequent adjustment of the machine is extremely simple and need not be described specially.

The reversing gear for driving the spindle 0 serves for being able to shape left-handedand right-handed screws. According to the kind of the blade the shaping must be commenced either on the right or on the left side, which makes it necessary for the feed spindle f to work in both directions, while the spindle 0 with the lever n and the face plates 0 always turns in the same direction. For this reason the reversing gear is neces sary and it is advisable to provide it with an idle center position, soas to allow to adjust the spindles 0 and f independently of each other. Now, under certain circumstances, it may be desirable to be able to shape also screws with a radially variable pitch, for instance such with an increasing pitch toward the middle, in order to utilize for propulsion to a greater extent the portions of the blade nearest to the nave, with a view to diminish the radius of the center of gravity of the attacking shearing forces and consequently the moment of flexure. In the machine just described the following further arrangement has therefore been made for the said purpose: The slide Z has, as seen in Fig. 4, a spindle o, by which the pivot m may be adjusted horizontally not only by the hand wheel q, but. also automatically by means of the worm gear to, the shaft y and the transmission gear 2 from the spindle 0. By these means the distance L may also be altered in relation with the radial displacement of the tool carriage a.

By a suitable selection of the conditions of transmission between the spindles 0 and 41 any desired and by law permissible alteration of the pitch in the radius may be obtained.

From the foregoing description results that all described forms of pressure surfaces may be shaped in an absolutely automatic manner and after themachine has once been adjusted and the work started it may be left to itself until the shaping of the pressure surface iscompleted.

What I claim is: 1. In a shaping machine for automatically working the pressure surfaces of screw propeller blades of the aforesaid kind, a

slidable cutting tool, rotary holders for holding the blade to be worked in such a position that the entering radius vector coincides with the axis of rotation of said holders, means for actuating said blade holders, driving means for moving said tool crosswise in a plane for the cutting operation, feeding means to feed the cutting tool transversely to its cutting movement, in a radial-direction of the blade, and interconnecting means between said holder actuating means and said feeding means to control the turning of the blade to be worked in a determinate ratio with the feed of the cutting tool so that the superficial portions of the blade pressure surface which are to be worked may fall successively within the cutting plane of the tool during the duration of the cut. i

2. In a shaping machine for automatically working the pressure surfaces of screw propeller blades of the aforesaid kind, a cutting tool, a slidable tool carriage, two rotary face plates for holding the blade to be'worked, longitudinally between them, driving means for moving said tool carriage crosswise for the cutting operation of the tool, a feed spindle for feeding the tool carriage transversely to the cutting movement of the tool, a lever mechanism geared with said rotary face plates to actuate them and gears between said feed spindle and said lever mechanism to transmit the feeding motion of the feed spindle to the lever mechanism and thereby to the rotary face plates, substantially as and for the purpose hereinbefore described. I

3. In a shaping machine for automatically working the pressure surfaces of screw propeller blades of the aforesaid kind, a cutting tool, a slidable tool carriage, two rotary face plates for holding the blade to be worked, longitudinally between them, driving means for moving said tool carriage crosswise for the cutting operation of the tool, a feed spindle for feeding the tool carriage transversely to the cutting movement of the tool, a lever geared with said rotary face plates to actuate them, a vertically movable slide, a connection between the latter and said lever, a vertical spindle arranged to operate said slide, and a change gear between this spindle and the tool carriage feeding spindle, substantially as and for the purpose hereinbefore described.

4. In a shaping machine'for automatically working j the pressure surfaces of screw propeller blades of the aforesaid kind, acuttingtool, a slidable tool carriage, two rotary face plates for holding the blade to be worked, longitudinally between them,

driving means for moving said tool car-- riage crosswise for the cutting operation of the tool, a feed spindle for feeding the tool carriage transversely to the cutting movement of the tool, a lever geared with said rotary face plates to actuate them, a verti cally movable slide, an adjustable connection between the latter and said lever a vertical spindle arranged to operate said slide, and a change gear between this spindle and the tool carriage feeding spindle, substantially as and for the purpose hereinbefore described.

5. In a shaping machine for automatically working the pressure surfaces of screw propeller blades of the aforesaid kind, a cutting tool, a slidable tool carriage, two rotary face plates for holding the blade to be worked, longitudinally between them, driving means for moving said tool carriage crosswise for the cutting operation of the tool, a feed spindle for feeding the tool carriage transversely to the cutting movement of the tool, a lever geared with said rotary face plates to actuate them, a vertically movable slide, an adjustable connecting pivot between said slide and said lever, a vertical spindle arranged to operate said slide, a change gear between this spindle and the tool carriage feeding spindle, a controlling device to automatically adjust said connecting pivot and an auxiliary gear between said controlling device and the slide operating spindle, substantially as and for the purpose hereinbefore described.

In witness whereof, I have hereunto signed my name in the presence of two subscribing witnesses.

ALBERT MUHLBERG.

Witnesses FRIOI-IES KLA BER,

W. BATY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). G. 

